Characterization of surface and excretory‐secretory antigens of Toxocara canis infective larvae

Abstract

The surface antigens of Toxocara canis infective larvae have been identified by radio-iodination and compared with the excretory-secretory (ES) products released by the larvae in vitro. Common antigens, of molecular weight 32 000 and 120 000 are found on the larval surface, in the ES material and in culture supernatant following surface iodination of living T. canis larvae. The 120 000 antigens consist of three closely migrating bands in each of these preparations. However, one prominent ES component, of molecular weight 400 000, is not found on the larval surface. Additional molecules of 55 000 and 70 000 are present in the ES material, but while these may be discerned in surface preparations there appears to be more heterogeneity of surface molecules in this size range. Both sets of molecules are antigens to infected patients and experimental animals. A comparison of characterized human sera show that a radio-immunoprecipitation assay correlates with the established ELISA test (r = 0.89), and that all labelled molecules are antigenic to the infected host.

Evaluation of an enzyme-linked immunoelectrotransfer blot test for the confirmatory serodiagnosis of human toxocariasis

“…The Toxocara larvae secrete a complex set of glycoproteins containing at least 50 distinct components, as enumerated by two-dimensional SDS-PAGE analysis (Page et al 1991(Page et al , 1992a, when maintained in vitro and probably in vivo (Maizels et al 1984, Maizels & Page 1990, Page et al 1992a. The major constituents of TES antigens are now characterized as mucins, C-type lectins and phosphatidylethanolamine-binding protein and are designated as TES-26, TES-32, TES-45, TES-55, TES-70, TES-120 and TES-400, according to their MWs on SDS-PAGE (Maizels et al 1984, Meghji & Maizels 1986, Gems et al 1995, Gems & Maizels 1996, Loukas et al 1999.…”

“…The major constituents of TES antigens are now characterized as mucins, C-type lectins and phosphatidylethanolamine-binding protein and are designated as TES-26, TES-32, TES-45, TES-55, TES-70, TES-120 and TES-400, according to their MWs on SDS-PAGE (Maizels et al 1984, Meghji & Maizels 1986, Gems et al 1995, Gems & Maizels 1996, Loukas et al 1999.…”

“…However, some components of TES antigens are not specific, demonstrating moderate cross-reactivity with other helminth species (Speiser & Gottstein 1984, Lynch et al 1988, Jacquier et al 1991, Nunes et al 1997. Sera from patients with ascariasis, filariasis, schistosomiasis and strongyloidiasis also react with TES antigens (Maizels et al 1984, Nunes et al 1999, Yamasaki et al 2000. In northern countries, the TES antigens are more specific for serodiagnosis of toxocariasis, but the level of specificity is unsatisfactory in countries where co-infections with other helminths are frequent.…”

In vitro production of Toxocara canis excretory-secretory (TES) antigen

“…This procedure was in accordance with that of AlcantaraNeves et al (2008). Maizels et al (1984) and Crowcroft and Gillespie (1991) induced embryonation of eggs by incubating the adult worms in formal saline for one month and the latter collected the eggs by homogenisation of the worms instead of dissection of worms. Different concentrations of sulphuric acid for inducing embryonation were also carried out (Oaks and Kayes 1979;Sugane and Oshima 1983;Gupta 1984 andWilliamson et al 1990).…”

“…Decortication of larvated eggs using different concentrations of sodium hypochlorite was tried elsewhere (Oaks and Kayes 1979;Maizels et al 1984;Bowman et al 1987;Williamson et al 1990;Crowcroft and Gillespie 1991;Roldan et al 2006 andPonce-Macotela et al 2011) whereas Iddawela et al (2007) used saturated calcium hypochlorite. Treatment of eggs with sodium hypochlorite to dissolve chitinous layer tended to mimic physiological conditions (Rajapakse et al 1992).…”